History of Earth (Silent Skies)
Archean Eon The earliest period of Earth's history not much survives dating from this far back in it's history. Early history A common theory about the formation of the Solar System (Including Earth) is the solar nebula hypothesis. In this model, the Solar system formed from a large, rotating cloud of interstellar dust and gas called the solar nebula. It was composed of hydrogen and helium created shortly after the Big Bang 13.8 Gya and heavier elements ejected by supernovae. About 4.5 Ga, the nebula began a contraction that may have been triggered by the shock wave of a nearby supernova. A shock wave would have also made the nebula rotate. As the cloud began to accelerate, its angular momentum, gravity and inertia flattened it into a protoplanetary disk perpendicular to its axis of rotation. After Formation During this time, the Earth's crust cooled too fast, it failed to form tectonic plates. This may have prevented cratonisation and continent formation. The lack of Archean rocks is a function of erosion and other natural processes. In contrast to the Proterozoic, Archean rocks are often heavily metamorphized deep-water sediments, such as graywackes, mudstones, volcanic sediments and banded iron formations. Greenstone belts are typical Archean formations, consisting of alternating high- and low-grade metamorphic rocks. The high-grade rocks were derived from volcanic island arcs, while the low-grade metamorphic rocks represent deep-sea sediments eroded from the neighboring island rocks and deposited in a forearc basin. In short, greenstone belts represent sutured protocontinents. The Earth's magnetic field failed establish at it's full strength due to the lack of a large iron core. The solar windflux was about 100 times the value of the modern Sun, so the lack of a strong magnetic field irradiated it's surface causing complex life (eukaryotes) to evolve much later, at about 1 Billion Years Ago. Formation of Oceans Gradual cooling prior to 3 Gya allowed for the formation of an outer crust, a portion of the lithosphere that encompasses the outer layer of Earth's physical structure, and the coolest part thereof. Composed of many different layers of chemical elements, it allowed for the formation of the planet's oceans. This global ocean of water, comprised mainly of liquid water, was formed following a long period called the late heavy bombardment in which the last of the large, non planet structures struck planets. During this period, comets, carrying frozen ice water, fell towards Earth (as well as Theia) and began to form small lakes. This continuing process went on for millions of years, during which time, Earth's early atmosphere and very weak magnetosphere allowed for this to continue somewhat unabattered by the Sun's solar storms with a higher radiation content than that found on Theia. Cryonian Eon 750 million years ago the Earth's poles shifted 90 degrees giving it a similar tilt to Uranus and freezing most of the planet's surface causing 90% of all life within the Earth's global ocean to freeze and go extinct this can be compared to the Permian Extinction in our timeline and after this the remaining 10% adapted to survive the freezing -10° celsius temperatures. Diravian warm period A short period between 700 to 690 million years ago in which Earth's surface temperature increased to 10°C which is a bit lower than Earth's average surface temperature but still warm enough to melt most of the sea ice, the cause of this sudden increase in temperature is still unknown but one theory states that increased volcanic activity may have pumped enough carbon dioxide to in Earth's average surface temperature inducing a global warming like effect, biodiversity temporarily rebounded from the sudden increase in temperature but this did not last long.